Since the advent of capacitors, there has been a need to measure the main magnitude of capacitors, i.e. the capacitance.
One known way to measure a capacitance is to connect an alternating current to the capacitor and observe the voltage.
Since an alternating current is used, the current could be affected by a mains current in the vicinity of the capacitor, the capacitor meter or cables connecting the two. It is known to select frequencies for the alternating current which is not a multiple of the mains frequencies 50 or 60 Hz. For example, it is known to select frequencies such as 111 Hz and 222 Hz, to reduce any effect of the fundamental frequencies and harmonics of the mains current. However, this strategy still allows for a significant interference from a mains current, whereby there is a need to further reduce interference from surrounding mains currents when measuring capacitance.